Manhole cover attaching means



J. H. DE FREES 2,783,913

. MANHOLE COVER ATTACHING MEANS March 5, 1957 2 Sheets-Sheet 1 FiledJuly 8. 1953 INVENTOR. V559 H Defksss March 5, 1957 J DE FREES 2,783,913

MANHOLE COVER ATTACHING MEANS Filed July 8, 1953' 2 Sheets-Sheet 2INVENTOR. JIOJEPH hi DEF/F656 A TTdRA/E'YJ United. States, Patent l eMANHOLE COVER ATTACHING Joseph H. De Frees, Warren, 2a., assignor toAnne De Frees, Warren, Pa.

Pl a J .8, 9 3 Ser a area 1 Claim. (Cl. 220-46) This invention relatesto safety tank closures, and particularly to novel and improved clampingmeans for'attachingsuch closure to the tank shell. A

An object of the invention is to provide novel clamping means which islight in weight and exceptionally easyto remove.

A further object of the invention is to provide closure means includingnovel clamping means which allows rapid removal of the closure, givingclear and unobstructed access to the interior, and avoids the necessityof wrench manipulation within the tank, a disadvantage inherent in manyformer closures of this general type. As is known to those skilled inthis art, the careless or vigorous use of a wrench inside a tank whichmay be filled with inflammable or explosive vapors is a potent source ofaccidents from sparking.

A further object of the invention is to provide in combination, closuremeans for a tank, and clamping means therefor, of such character thatthe opening to the tank interior is free from bothersome obstructions,such as wing nuts, springs, bolt ends, or other necessary adjuncts offormer structure, which have interfered with the normal uses of the fillopening, when opened.

Other objects and advantages will be apparent from a study of thepresent specification, in conjunction with the accompanying drawings,showing one embodiment of the invention, in which:

Fig. 1 is a top plan view of a manhole cover closure, with clampingmeans thereon in accordance with my invention.

Fig. 2 is a view, greatly enlarged, taken on the line 2--2 of Fig. 1.

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 1.

Fig. 4 is a vertical sectional view taken on the line 4--4 of Fig. 3.

Fig. 5 is a top plan view and Fig. 6 is a bottom plan view of the ventvalve shown in Fig. 4.

Referring now to the drawings I show a fragmentary portion of the upperwall of a storage or transportation tank 10 formed from sheet metal.This wall is provided, as is usual, with a manhole defined by an annularneck 11, also of sheet metal, which is welded or otherwise suitablyattached to top wall 10 in leak-proof fashion. This annular neck has anoutturned flange 12 around its upper periphery, said flange beingpreferably in a flat plane since it serves as a seat member, as willappear. A cover plate 13 is provided to seal the manhole opening, andallow for automatic venting in both directions. The present inven tionof course resides in the means for ready removal of the cover plate 13and associated mechanical elements. Such elements include means forsupporting a venting unit, said means comprising a cross bar 14 hingedat 15 on a lug 16 attached to cover 13. The cross bar carries the venthousing 17 which has a threaded connection with a boss 18 on the crossbar. The vent housing carries a discoidal plate 19, a circular gasket 20of sealing material and a 2,783,913 Patented Mar. 1957 2 retainingplate21, the purpose of which assembly is to normally seal a filling opening22 in plate 13.

The function and operation of this filler sealvand vent device is asfollows. Within housing 17, and retained by cap 25 'is a mesh screen 26supporting a light spring 27 which maintains on its top a ball valveunit. This unit comprises two nested cups 2-8 and 29, cup'29beingfixed'in housing 25 by means of arms 29a. Cup 29 carries a ball 30normallydownwardly seating by gravity in the neck 29a. Cup 28-carries aball 31' normally lying inactively in its cup bottom, but adapted toseal theaperture 32 if the tank'rolls upside down.

Any vapor pressure within the tank passes through screen'2 6 andneck 29aandraisesballfiil. It then passes between cups '28 and 29, and throughapertures 33 (of which there are four) in the wall of cup'28, thereafterescaping through aperture 32. Should the pressure within thetan'ksuddenly drop by reason ofdumpingor discharge of liquid fromthetank, the base plate 34will compress spring 27 thereby'permitting'immediate pressure equalization. If the tank is involved in an accidentso as to be overturned, ball 31 will drop and seal aperture 32 so as toprevent liquid escape.

When clamped as shown, and soon to be described, plate 19 is normallyimmovably sealed. If unexpectedly heavy pressure suddenly developswithin the tank, for example in case of fire, the strength andflexibility of plate 19 are so controlled and designed that said platewill deflect at any pressure in excess of a predetermined amount, forexample three to four pounds per square inch, and thus plate 19 servesas a giant pop valve. If, as hereinabove mentioned, the tank overturns,plate 19 is sufficiently firmly clamped to retain the static head of theliquid load, and only an excessive pressure arising from rapidcombustion will be relieved by flexure of plate 19.

The cross bar 14 is locked in place by a lock lever 35 pivoted at 36 ona lug 37 attached to cover plate 13. Lever 35 has an opening 33 throughwhich the tongue 14a of lever 14 extends when the parts are in closedposition, and levers 35 and 14 have cooperating shoulders which snapinto retaining abutment and maintain peripheral edge contact around theedge of the filling aperture 22.

It will be apparent that for normal service use, involving mostly thefilling of the tank, the opening operation, first of the lock lever 35and then the cross bar 14, lifts the venting unit and the associateddiscs 19, 2t), and 21.

For internal service of any kind it is desirable to remove the whole topplate 13, which is usually retained securely in place in the followingway.

Referring particularly to Figs. 1 and 2, the peripheral flange 12 ofneck 11 has an annular gasket 40 of U-shaped transverse section snappedthereon. The gasket is formed from resilient, rubber-like material andhas lateral edge beads 40a and 401) which serve as strengtheningretainers, and the bead 40a takes the sealing pressure, as will appear,because cover plate 13 rests on bead 40a.

For securely clamping plate 13 and flange 12 together I provide a splitclamping ring 43 of channeled contour in section, which is here shown asirregular U-contour in section. At the split each end is provided withclips or blocks 43a and 43b which are tunneled to receive the shank of abolt 44, retained by a clamping nut 45. Slacking off the nut 45 permitsready removal of ring 43 which is actually biased to spring opensuiiiciently to permit its removal from the plate 13 and flange 12.

In prior constructions the main cover plate, corresponding to presentmember 13, was usually attached by internal bolts, and removal of suchplate necessitated removal of a number of bolts, usually six in number,which was a time-consuming activity and manipulation of tools on theinner surface of the tank top could well result in striking sparks fromthe ferrous metal portions of the structure, which would be most seriousin the presence of certain airvapor mixtures. With my invention theattaching and detaching operations are performed while the cover plate13 is resting on gasket 40, so as to minimize explosion dangers, orsubjection of workmen to noxious fumes.

In the present embodiment the clips 43a and 43b are simple pieces ofsheet metal, bent to the shape shown in Fig. 2, and welded in place. Thering 43 is also shaped from sheet metal. Any channeled contour, openinginwardly, which suits the arrangement of the parts to be clamped, willbe quite adequate, provided its shape is such as to exert a wedged gripon the flange 12 and the edge of plate 13 when the clamp is tightened.

. What I claim is: I H

Closure and clamping means for a manhole aperture in a tank comprising aperipheral outturned flange fixed around said aperture in a horizontalplane, a closure member overlying said flange and having acircumferential horizontal rim portion also in a horizontal plane, saidflange and said rim portion having registered peripheral edge portions,an annular gasket of ruhbcrlike material and of U-shaped sectionalcontour peripherally embracing said flange edge portion in such mannerthat one of the legs of the U-shaped gasket lies between said flange andsaid rim portion, and the other leg lies below said flange, a split ringmember of channeled contour opening inwardly and gripping said edgeportions, one leg of said channel having a substantially planar surfacewhich lies above said rim and contacts the same, and the other leg ofsaid channel extending downwardly and inwardly and having an innersurface extending at an acute angle to the first said planar surface,said inner surface contacting a peripheral outer portion of said gasket,and cooperating means on each end of said ring on each side of saidsplit for drawing said ends together to maintain said grip.

References Cited in the file of this patent UNITED STATES PATENTS1,449,940 Hackney Mar. 27, 1923 1,640,430 Stanley Aug. 30, 19271,754,776 Stanley Apr. 15, 1930 1,904,09l Shoop Apr. 18, 1933 1,969,120Coackley Aug. 7, 1934 2,226,396 Wackman Dec. 24, 1940 2,486,565 Kojan eta1 Nov. 1, 1949 2,633,616 Kohout Apr. 7, 1953

